ROCKSTRO, WILLIAM SMITH (1823–1895), musical composer and theorist, was born on 5 Jan. 1823 at North Cheam, Surrey, and baptised at Morden church in the name of Rackstraw. Rockstro was an older form of the surname, which the composer resumed in early life. His first professional teacher was John Purkis, the blind organist, and his first recorded composition brought forward publicly was a song, ‘Soon shall chilling fear assail thee,’ which Staudigl sang at F. Cramer's farewell concert on 27 June 1844. About the same time he officiated as organist in a dissenting chapel in London, and received instruction from Sterndale Bennett. Apparently on Bennett's recommendation, he studied at the Leipzig Conservatorium from 20 May 1845 until 24 June 1846. He was one of seven specially selected pianoforte pupils of Mendelssohn, with whom he also studied composition, and whose intimacy he enjoyed. His studies with Hauptmann laid the foundation of his great theoretical knowledge, and from Plaidy he received the finest traditions of pianoforte technique.

On his return to England he lived for some time with his mother in London, and was successful as a pianist and teacher. In connection with a series of ‘Wednesday concerts’ he came into contact with Braham and other famous singers, from whom he acquired the best vocal traditions of that day. He wrote at the period a number of beautiful songs, some of which, such as ‘Queen and Huntress’ and ‘A jewel for my lady's ear,’ became in a sort classical. He edited for the firm of Boosey & Co. a series of operas in vocal score, under the title of ‘The Standard Lyric Drama,’ which were the earliest to be published at moderate price, and which contained the valuable innovation of noting prominent orchestral effects above the pianoforte part. For many years Rockstro was chiefly known to the musical world as the composer of pianoforte fantasias, transcriptions, and drawing-room pieces, which he continued to produce after he left London for Torquay, a change made on account of his own and his mother's health. He also enjoyed a high reputation as a teacher of singing and the pianoforte, and from 1867 was organist and honorary precentor at All Saints Church, Babbacombe. On the death of his mother in 1876, he openly joined the church of Rome.

On musical archæology Rockstro ultimately concentrated most of his attention, and in that branch of the art he soon had no rival among his contemporaries. His ‘Festival Psalter adapted to the Gregorian Tones,’ with T. F. Ravenshaw (1863), and ‘Accompanying Harmonies to the Ferial Psalter’ (1869), did much to promote the intelligent study of ancient church music. Two examples may be given of his insight into the methods and style of the great Italian contrapuntists, and more especially of Palestrina. A composition which he sent in anonymously to a competition held by the Madrigal Society about 1883 was so closely modelled upon Palestrina's work that the presiding judge rejected it on the ground that it must have been literally copied. It is the beautiful madrigal ‘O too cruel fair,’ perhaps the best example of Rockstro's work as a composer. On another occasion, in scoring a sacred work by Palestrina, an hiatus of considerable length was discovered in one of the only set of parts then known to exist in England. The missing portion was conjecturally restored by Rockstro, and on the discovery of a complete copy the restoration was found to represent the original exactly.

But Rockstro's deep and practical knowledge of the ancient methods of composition, of modal counterpoint, and of the artistic conditions of old times, was only imperfectly turned to account—in some useful little manuals on harmony (1881) and counterpoint (1882)—until the publication of Sir George Grove's ‘Dictionary of Music and Musicians,’ to which he contributed many articles on subjects connected with ecclesiastical music and the archæological side of music. In 1886 Rockstro published a valuable ‘General History of Music,’ and produced with little success an oratorio, ‘The Good Shepherd,’ at the Gloucester Festival, under his own direction. His literary work increased as years went on, and he finally settled in London in 1891, where, in spite of failing health, he achieved not only much work as a teacher, but delivered lectures at the Royal Academy of Music and the Royal College, and was appointed at the latter institution teacher of a class for counterpoint and plain-song. He died in London on 2 July 1895.

Besides the writings already enumerated, and a few short stories published in 1856–8, Rockstro's chief works were: 1. ‘A History of Music for Young Students’ (1879). 2. ‘The Life of George Frederick Handel’ (1883). 3. ‘Mendelssohn’ (Great Musicians Series, 1884). 4. ‘Jenny Lind the Artist’ (in collaboration with Canon Scott Holland, 1891; abridged edition, 1893). 5. ‘Jenny Lind, her Vocal Art and Culture’ (partly reprinted from the biography, 1894).